theorem
  (P!l).(x,y) = P!CQC_Subst(l,Sbst(x,y)) & QuantNbr(P!l) = QuantNbr((P!l
  ).(x,y))
proof
  set S = [P!l,Sbst(x,y)];
  S = Sub_P(P,l,Sbst(x,y)) by SUBSTUT1:9;
  then
A1: (P!l).(x,y) = P!CQC_Subst(l,Sbst(x,y)) by SUBLEMMA:8;
  QuantNbr(P!CQC_Subst(l,Sbst(x,y))) = 0 by CQC_SIM1:15;
  hence thesis by A1,CQC_SIM1:15;
end;
